The invention relates to tubular winding cores about which various materials are wound into rolls, and methods of making winding cores, wherein the cores are configured to facilitate rolls of wound materials being axially stacked end-to-end so they remain coaxial with one another.
Web materials such as paper, plastic film, metal foil, and others, are commonly provided to web converters (e.g., printers, laminators, surface treaters, packaging manufacturers, etc.) in the form of large rolls of the material. The web material is wound about tubular winding cores, which typically are formed of paperboard. It is a common practice to ship multiple rolls of material stacked vertically end-to-end in two or more layers on a pallet. A corrugated paper or plastic separator or slip sheet is positioned between adjacent layers to prevent the rolls from rubbing together and damaging the edges of the web material. The separators or slip sheets increase the cost of shipping the web material.